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Pythia8Hadronisation.cc

Go to the documentation of this file.

#include <algorithm>
#include <iostream>
#include <iterator>
#include <sstream>
#include <string>
#include <memory>
#include <assert.h>

#include <boost/shared_ptr.hpp>

#include <HepMC/GenEvent.h>
#include <HepMC/GenParticle.h>

#include <Pythia.h>
#include <LesHouches.h>
#include <HepMCInterface.h>

#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/ServiceRegistry/interface/Service.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/Utilities/interface/RandomNumberGenerator.h"

#include "SimDataFormats/GeneratorProducts/interface/LesHouches.h"
#include "GeneratorInterface/LHEInterface/interface/LHERunInfo.h"
#include "GeneratorInterface/LHEInterface/interface/LHEEvent.h"
#include "GeneratorInterface/LHEInterface/interface/Hadronisation.h"

using namespace Pythia8;

namespace lhef {

class Pythia8Hadronisation : public Hadronisation {
    public:
        Pythia8Hadronisation(const edm::ParameterSet &params);
        ~Pythia8Hadronisation();

    private:
        void doInit();
        std::auto_ptr<HepMC::GenEvent> doHadronisation();
        void newRunInfo(const boost::shared_ptr<LHERunInfo> &runInfo);

        const int                               pythiaPylistVerbosity;
        int                                     maxEventsToPrint;
        std::vector<std::string>                paramLines;

        class LHAupLesHouches;

        std::auto_ptr<Pythia>                   pythia;
        std::auto_ptr<LHAupLesHouches>          lhaUP;
        std::auto_ptr<HepMC::I_Pythia8>         conv;
};

class Pythia8Hadronisation::LHAupLesHouches : public LHAup {
    public:
        LHAupLesHouches(Hadronisation *hadronisation) :
                                        hadronisation(hadronisation) {}

        void loadRunInfo(const boost::shared_ptr<LHERunInfo> &runInfo)
        { this->runInfo = runInfo; }

        void loadEvent(const boost::shared_ptr<LHEEvent> &event)
        { this->event = event; }

    private:

        bool setInit();
        bool setEvent(int idProcIn);

        Hadronisation                   *hadronisation;
        boost::shared_ptr<LHERunInfo>   runInfo;
        boost::shared_ptr<LHEEvent>     event;
};

bool Pythia8Hadronisation::LHAupLesHouches::setInit()
{
        if (!runInfo)
                return false;
        const HEPRUP &heprup = *runInfo->getHEPRUP();

        setBeamA(heprup.IDBMUP.first, heprup.EBMUP.first,
                 heprup.PDFGUP.first, heprup.PDFSUP.first);
        setBeamB(heprup.IDBMUP.second, heprup.EBMUP.second,
                 heprup.PDFGUP.second, heprup.PDFSUP.second);
        setStrategy(heprup.IDWTUP);

        for(int i = 0; i < heprup.NPRUP; i++)
                addProcess(heprup.LPRUP[i], heprup.XSECUP[i],
                           heprup.XERRUP[i], heprup.XMAXUP[i]);

        hadronisation->onInit().emit();

        runInfo.reset();
        return true;
}

bool Pythia8Hadronisation::LHAupLesHouches::setEvent(int inProcId)
{
        if (!event)
                return false;
        const HEPEUP &hepeup = *event->getHEPEUP();

        setProcess(hepeup.IDPRUP, hepeup.XWGTUP, hepeup.SCALUP,
                   hepeup.AQEDUP, hepeup.AQCDUP);

        for(int i = 0; i < hepeup.NUP; i++)
                addParticle(hepeup.IDUP[i], hepeup.ISTUP[i],
                            hepeup.MOTHUP[i].first, hepeup.MOTHUP[i].second,
                            hepeup.ICOLUP[i].first, hepeup.ICOLUP[i].second,
                            hepeup.PUP[i][0], hepeup.PUP[i][1],
                            hepeup.PUP[i][2], hepeup.PUP[i][3],
                            hepeup.PUP[i][4], hepeup.VTIMUP[i],
                            hepeup.SPINUP[i]);

        const LHEEvent::PDF *pdf = event->getPDF();
        if (pdf)
                this->setPdf(pdf->id.first, pdf->id.second,
                             pdf->x.first, pdf->x.second,
                             pdf->scalePDF,
                             pdf->xPDF.first, pdf->xPDF.second);

        hadronisation->onBeforeHadronisation().emit();

        event.reset();
        return true;
}

Pythia8Hadronisation::Pythia8Hadronisation(const edm::ParameterSet &params) :
        Hadronisation(params),
        pythiaPylistVerbosity(params.getUntrackedParameter<int>("pythiaPylistVerbosity", 0)),
        maxEventsToPrint(params.getUntrackedParameter<int>("maxEventsToPrint", 0))
{
        std::vector<std::string> setNames =
                params.getParameter<std::vector<std::string> >("parameterSets");

        for(std::vector<std::string>::const_iterator iter = setNames.begin();
            iter != setNames.end(); ++iter) {
                std::vector<std::string> lines =
                        params.getParameter< std::vector<std::string> >(*iter);

                for(std::vector<std::string>::const_iterator line = lines.begin();
                    line != lines.end(); ++line )
                        if (line->substr(0, 14) == "Random:setSeed" ||
                            line->substr(0, 11) == "Random:seed")
                                throw cms::Exception("PythiaError")
                                        << "Attempted to set random number"
                                           " using Pythia command 'MRPY(1)'."
                                           " Please use the"
                                           " RandomNumberGeneratorService."
                                        << std::endl;

                std::copy(lines.begin(), lines.end(),
                          std::back_inserter(paramLines));
        }
}

Pythia8Hadronisation::~Pythia8Hadronisation()
{
}

void Pythia8Hadronisation::doInit()
{
        pythia.reset(new Pythia);
        lhaUP.reset(new LHAupLesHouches(this));
        conv.reset(new HepMC::I_Pythia8);

        for(std::vector<std::string>::const_iterator iter = paramLines.begin();
            iter != paramLines.end(); ++iter)
                if (!pythia->readString(*iter))
                        throw cms::Exception("PythiaError")
                                << "Pythia did not accept \""
                                << *iter << "\"." << std::endl;

        edm::Service<edm::RandomNumberGenerator> rng;
        std::ostringstream ss;
        ss << "Random:seed = " << rng->mySeed();
        pythia->readString(ss.str());
        pythia->readString("Random:setSeed = on");
}

// naive Pythia8 HepMC status fixup
static int getStatus(const HepMC::GenParticle *p)
{
        int status = p->status();
        if (status > 0)
                return status;
        else if (status > -30 && status < 0)
                return 3;
        else
                return 2;
}

std::auto_ptr<HepMC::GenEvent> Pythia8Hadronisation::doHadronisation()
{
        lhaUP->loadEvent(getRawEvent());
        if (!pythia->next())
                throw cms::Exception("PythiaError")
                        << "Pythia did not want to process event."
                        << std::endl;

        std::auto_ptr<HepMC::GenEvent> event(new HepMC::GenEvent);
        conv->fill_next_event(pythia->event, event.get());

        for(HepMC::GenEvent::particle_iterator iter = event->particles_begin();
            iter != event->particles_end(); iter++)
                (*iter)->set_status(getStatus(*iter));

        event->set_signal_process_id(pythia->info.code());
        event->set_event_scale(pythia->info.pTHat());

        if (maxEventsToPrint > 0) {
                maxEventsToPrint--;
                if (pythiaPylistVerbosity)
                        pythia->event.list(std::cout);
        }

        return event;
}

void Pythia8Hadronisation::newRunInfo(
                                const boost::shared_ptr<LHERunInfo> &runInfo)
{
        lhaUP->loadRunInfo(runInfo);
        pythia->init(lhaUP.get());
}

DEFINE_LHE_HADRONISATION_PLUGIN(Pythia8Hadronisation);

} // namespace lhef

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